Preload system for bearings in a waterjet propulsion apparatus

Abstract

A preload system for bearings in a waterjet propulsion apparatus, the apparatus including a water intake section and a pumping unit including a bearing cartridge. The bearing cartridge is designed such that during operation a preload system provides tailoring between radial and axial thermal growths of a plurality of bearing components that comprise the bearing cartridge and such that an initial ambient temperature preload condition can be maintained or reduced during normal water mode operation conditions. The preload system includes a plurality of spacers that when positioned relative to the bearing components of the bearing cartridge prevent relative motion between the bearing components during land mode operation and maintain or reduce the initial ambient room temperature preload condition during normal water mode operation.

Description

FIELD OF THE INVENTION [0001] The present invention relates generally to waterjet propulsion apparatus. More particularly, the present invention relates to an improved waterjet propulsion apparatus including a thermally insensitive solid bearing preload system. BACKGROUND OF THE INVENTION [0002] The main components of a waterjet propulsion apparatus are an intake section, a pump or pumping unit, and a nozzle. Fluid enters the unit through the intake section, which scoops water into the apparatus and directs it in the aft direction. The pump includes a rotor, also referred to as an impeller, and a stator located downstream thereof, both of which are located within a fluid conduit or flowpath. The rotor is turned on a stationary spindle and is driven by the prime mover of the vehicle. The rotor adds energy to the fluid, which accelerates the fluid to a higher velocity and pressure. The swirl induced by the rotor is for the most part removed by the stator, which does not rotate. At the...

AI Technical Summary

Benefits of technology

[0006] There has now been developed a waterjet propulsion apparatus including a preload system for the bearings that satisfies one or more of the above-noted deficiencies. In one embodiment, the waterjet propulsion apparatus includes a waterjet propulsion apparatus comprising a housing having at least a fluid intake section and a pumping unit disposed within the housing and in fluidic communication with the fluid intake section. The pumping unit comprising a rotor including a plurality of rotor blades coupled to a rotor hub and having a bearing cartridge having an initial ambient temperature preload condition. The bearing cartridge comprised of a plurality of bearing components. The pumping unit further comprises a stator having a fluid inlet disposed adjacent to and downstream of the rotor and a fluid outlet disposed downstream of the stator. The bearing cartridge further includes a thermally insensitive solid bearing preload system comprising a bearing support system that is preloaded using a plurality of spacers to prevent relative motion between the plurality of bearing components that comprise the bearing cartridge and provide adjustment of the initial preload condition at ambient temperatures.

[0007] In a further embodiment, still by way of example only, there is provided a pumping unit for a waterjet propulsion apparatus comprising a rotor comprising a plurality of rotor blades coupled to a rotor hub and having a bearing cartridge coupled to the rotor. The bearing cartridge having an initial ambient temperature preload condition and comprised of a plurality of bearing components. The pumping unit further comprising a stator having a fluid inlet disposed adjacent to the rotor, and a fluid outlet disposed downstream of the stator. The bearing cartridge comprises a bearing cavity. The plurality of bearing components are housed within a bearing cavity and comprise a bearing assembly having at least a plurality of roller bearing elements supported by a plurality of races, a bearing spindle, an outer ring, and a retainer. The bearing cartridge further includes a thermally insensitive solid bearing preload system comprising a bearing support system that is preloaded using a plurality of spacers to prevent relative motion between the plurality of roller bearing elements, the plurality of races, the outer ring, and the retainer and provide adjustment of initial preload condition at ambient temperature in response to radial and axial thermal growths of the plurality of bearing components.

[0008] In still a further embodiment, and still by way of example only, there is provided a pumping unit for a waterjet propulsion apparatus comprising a rotor comprising a plurality of rotor blades coupled to a rotor hub, a stator having a fluid inlet disposed adjacent to the rotor, and a fluid outlet disposed downstream of the stator and a bearing cartridge coupled to the rotor. The bearing cartridge having an initial ambient temperature preload condition. The bearing cartridge comprising a bearing cavity having a plurality of bearing components housed within the bearing cavity. The plurality of bearing components comprising a bearing assembly having at least a plurality of roller bearing elements supported by a plurality of races and a retainer. The bearing cartridge further includes a thermally insensitive solid bearing preload system comprising a retainer clamp spacer positioned to maintain a distance between the plurality of roller bearing elements and a shaft spacer positioned to maintain a distance between a clamping nut and the plurality of roller bearing elements, the retainer clamp spacer and the shaft spacer preventing relative motion between the plurality of roller bearing elements, the plurality of races, and the outer ring in the bearing assembly and providing adjustment of the initial ambient temperature preload condition in response to radial and axial thermal growths of the plurality of roller bearing elements, the plurality of races, the outer ring, the retainer, the spindle, the retainer clamp spacer and the shaft spacer.

Problems solved by technology

Typically, in the design of the waterjet propulsion apparatus, the rotor system may not be heavy enough to generate a sufficient reaction preload between the bearings in a water mode.

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